Multi-hyphenate Onur Tukel returns to the Tribeca fest with his seventh feature, a comedy so dark that only minimal humor alleviates the film’s dour perspective. Further festival play and limited theatrical support can probably be expected in the New York area, although digital platforms may offer the best alternatives elsewhere.

Tukel plays Ron, a forty-ish high-school history teacher who is clearly struggling: his teenage students are constantly disrespecting him, he’s practically estranged from his judgmental wife Nicki (Trieste Kelly Dunn) and his best friend Les (Max Casella) constantly gives him a hard time about his antisocial behavior. But things are about to get a whole lot worse after radio talk-show host Stevie Bricks’ (Dylan Baker) weekly “Tell-All Tuesday” program prompts Ron to reveal to his wife and friends that while in college an altercation over another man’s girlfriend resulted in Ron slamming a door on the guy’s hand, severing two fingers.

Somehow he considers that transgression worse than failing to reveal that he fooled around with Les’ wife Kate (Jennifer Prediger) one drunken evening, a fact that she discloses to her husband in a further round of questionably advisable confessions. Ron hardly notices that his marriage is headed for far deeper trouble once someone begins targeting him with random body parts, however. First a bloody finger arrives in the mail, then a severed foot turns up in a coin-op drier when he’s doing the laundry. As his paranoia escalates, almost nobody escapes Ron’s accusations.

Les is at the top of his list, suspected of seeking revenge because Ron seduced Kate. After harassing a student he also considers a potential perpetrator, Ron gets suspended from work, even as he wonders whether his own wife may be secretly retaliating for his infidelity. His hostility quickly becomes so pronounced that almost everyone he comes into contact with falls under suspicion, a sure sign that a major crisis is imminent.

Eschewing the campy comedy that characterized his Tribeca entry Summer of Blood last year, Tukel’s script takes such an unfavorable view of human nature that it’s difficult to identify any likeable characters, most of whom are constantly scheming to manipulate and discredit one another. As the principal instigator, Tukel bestows Ron with an outsize share of unpleasant qualities that are elaborated with a tiresomely repetitive performance that draws the supporting cast into a diminishing spiral of criticism and retribution. Their sometimes vague motivations and a series of implausible plot developments are further off-putting factors periodically derailing the narrative, which consistently struggles to connect, despite the film’s passable indie-production aesthetic.